SPEAKER AND DEVICE USING THIS SPEAKER
A speaker of the present invention includes a frame at which a magnetic circuit is mounted, a voice coil, an arched diaphragm, and an edge made of material different from that of the diaphragm. A part of the voice coil is disposed at a magnetic gap formed by the magnetic circuit. The diaphragm is coupled with the voice coil, and the edge links the diaphragm with the frame. Further, the diaphragm includes an inner-diameter-fixing part to be joined with the voice coil, an outer-diameter-fixing part to be joined with the edge, and a top part formed between the inner-diameter-fixing part and the outer-diameter-fixing part to protrude forward. A part near the top part differs from a part other than the part near the top part of the diaphragm in at least one of thickness and density. This structure flattened sound-pressure-frequency characteristic over broad bands.
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The present invention relates to a speaker used in various acoustic devices or image devices, an electric device such as a stereo system or a TV set and a device of an automobile or the like.
BACKGROUND ARTAs a conventional method for extending a high threshold frequency of a speaker, a method described in “SPEAKER SYSTEM vol. 1 pp. 157-158 written and edited by Takeo Yamamoto and published by Radio Technology Company (International Standard Book Number: ISBN4844301144)” (hereinafter referred to as “document 1”) is well-known. According to the document 1, an effective method is, for example, as follows: 1. Making a vibration-system-base mass light; 2. Using a diaphragm having high stiffness; 3. Making a half apical angle of a diaphragm small at a joining portion between the diaphragm and a voice coil.
However, the vibration-system-base mass such as the diaphragm or the voice coil becomes lighter, strength of the diaphragm decreases. Therefore, dividing resonance of the diaphragm tends to be generated, and a lot of large peaks and dips occur at a sound-pressure-frequency characteristic of the speaker. Moreover, durability against input signals can not be high.
In general, high stiffness material has a small internal loss, and large peaks and dips occur at its sound-pressure-frequency characteristic. Furthermore, when the half apical angle becomes small, gentle-and-large peaks and dips occur at the sound-pressure-frequency characteristic of anterior-chamber effect of the diaphragm.
Yet further, field magnet part 107 structured by a plate, a magnet and a yoke is disposed at a bottom of frame 105.
Because half apical angle θ of conventional speaker 100 structured mentioned above is small (i.e., not larger than 45 degrees), gentle-and-large peaks and dips occur at the sound-pressure-frequency characteristic.
The conventional speaker is, for example, disclosed in Unexamined Japanese Patent Publication No. H11-313390.
SUMMARY OF THE INVENTIONA speaker of the present invention includes a frame at which a magnetic circuit is mounted, a voice coil, an arched diaphragm, and an edge made of material different from that of the diaphragm. A part of the voice coil is disposed at a magnetic gap formed by the magnetic circuit. The diaphragm is coupled with the voice coil, and the edge links the diaphragm with the frame. Further, the diaphragm includes an inner-diameter-fixing part to be joined with the voice coil, an outer-diameter-fixing part to be joined with the edge, and a top part formed between the inner-diameter-fixing part and the outer-diameter-fixing part to protrude forward. A part near the top part differs from a part other than the part near the top part of the diaphragm in at least one of thickness and density. Using the structure discussed above, the speaker having a flat sound-pressure-frequency characteristic ranging over broad bands can be realized.
- 1 diaphragm
- 1A inner-diameter-fixing part
- 1B outer-diameter-fixing part
- 1C top part of the diaphragm
- 1D part near the top part
- 2 center cap
- 3 voice coil
- 3A voice loading coil
- 4 damper
- 5 frame
- 6 edge
- 7 field magnet part
- 8 magnetic gap
- 30 speaker
- 40 electronic circuit
- 41 circuit board
- 42 electronic component
- 43 amplifier circuit
- 50 speaker module
- 51 enclosure
- 52 amplifier
- 53 player
- 54 mini component system
- 55 speaker system
- 56 main body
- 60 automobile
- 61 rear tray
- 62 front panel
- 63 driving member
- 64 steering
- 65 body
- 66 front wheel
- 67 rear wheel
- 68 seat
- 100 speaker
- 101 diaphragm
- 102 center cap
- 103 voice coil
- 104 damper
- 105 frame
- 106 edge
- 107 field magnet part
Exemplary embodiments of the present invention are demonstrated hereinafter with reference to the accompanying drawings.
FIRST EXEMPLARY EMBODIMENTAs shown in
Outer-diameter-fixing part 1B is coupled with edge 6 made of cloth. Edge 6 is coupled with frame 5, thereby coupling diaphragm 1 with frame 5. Inner-diameter-fixing part 1A is coupled with voice coil 3, thereby forming a joining portion. Half apical angle θ1 which is an angle coupling diaphragm 1 with voice coil 3 is not larger than 45 degrees. An outer periphery part of voice coil 3 is held at its center by damper 4. Further, damper 4 is fixed to frame 5. Still further, center cap 2 is fixed to a top part of voice coil 3.
Yet further, as a magnetic circuit, field magnet part 7 structured by a plate, a magnet and a yoke, is disposed at a bottom of frame 5. Voice loading coil 3A wound at a lower part of voice coil 3 is inserted and placed in magnetic gap 8 structured by the plate and the yoke.
Operation of speaker 30 structured discussed above is described hereinafter.
Relation between high threshold frequency Fh of a speaker and half apical angle θ is disclosed in document 1. In a word, in a case of a model of the speaker shown in
m1: mass of a voice coil [kg]
m2: mass of a diaphragm [kg]
Sn: stiffness of a base of a diaphragm=π·E·h·cos2 θ/sin θ
E: Young's modulus of the diaphragm [N/m2]
h: a thickness of the base of the diaphragm [m]
θ: a half apical angle of the diaphragm [deg]
In short, it is effective to make half apical angle θ small for extending high threshold frequency Fh. However, in general, small half apical angle θ makes a total height of the diaphragm higher. In addition, small half apical angle θ generates gentle-and-large peaks and dips at a sound-pressure-frequency characteristic by anterior-chamber effect of forward space ranging from a front surface of the diaphragm to a fixing part of the diaphragm. Accordingly, the speaker having half apical angle θ larger than 45 degrees is common.
On the contrary, because diaphragm 1 is formed in curved surface, forward space from a front surface of diaphragm 1 to top part 1C of the diaphragm is small, even when half apical angle θ1 is not larger than 45 degrees. Further, strength of diaphragm 1 can be improved by controlling a curving state of diaphragm 1. As a result, thinner speaker 30 can be realized, and generation of dividing resonance of diaphragm 1 is restricted.
In a case where the diaphragm is made of single material, if the material is soft, stiffness of the diaphragm becomes insufficient, so that reproduction at a high frequency band becomes difficult. On the other hand, if the material is hard, flexibility becomes insufficient, so that reproduction at a low frequency band becomes difficult. In a word, reproduction of sound-pressure-frequency at broad bands ranging from a low band to a high band is difficult.
However, edge 6 is fixed to outer-diameter-fixing part 1B, thereby coupling diaphragm 1 with frame 5. Edge 6 is made of cloth or the like different material from diaphragm 1. Because material having Young's modulus lower than that of diaphragm 1 is used in edge 6, vibration at a low frequency band is difficult to be attenuated. If edge 6 has a shape in such a manner that vibration at a low frequency band is difficult to be attenuated, it is more effective. By using this structure, amplitude for reproducing a low frequency is secured. In short, a high reproducing threshold frequency is extended by the material, shape and half apical angle of diaphragm 1. In addition, reproduction of the low frequency is realized by using edge 6. Therefore, frequencies at broad bands ranging from a low frequency to a high frequency are reproduced as a flat frequency characteristic.
Measured sound-pressure-frequency characteristics are demonstrated hereinafter with reference to its characteristic view.
According to the sound-pressure-frequency characteristic of speaker 100 in
On the other hand, as shown at characteristic curve A of the sound-pressure-frequency characteristic of speaker 30, high threshold frequency is high enough (i.e., 30 kHz) and exceeds audible frequency bands. Further, peaks and dips caused by anterior-chamber effect or dividing resonance of diaphragm 1 are reduced considerably. Still further the lowest resonance frequency F0 is 200 Hz, which is extremely low as compared with the characteristic of speaker 100.
As discussed above, according to speaker 30 of the present invention, diaphragm 1 has an arched shape, so that diaphragm 1 can be thinner even when half apical angle θ1 is small. Therefore, anterior-chamber effect is restricted. Further, strength of diaphragm 1 improves, so that dividing vibration is difficult to be generated. As a result, speaker 30 itself can be thinner. In addition, the high threshold frequency extends and the sound-pressure-frequency characteristic flattens. In addition, by fixing outer-diameter-fixing part 1B to edge 6 made of soft material, the lowest resonance frequency of speaker 30 extends to a low frequency area. By using this structure, the sound-pressure-frequency characteristic can be flattened over broad frequency bands.
According to the first embodiment, kraft pulp is used as material of diaphragm 1. However, material of diaphragm 1 is not limited to this, and diaphragm 1 may be formed with wood fiber including sulfite pulp alone or combination of kraft pulp and sulfite pulp. Further, reinforcing agent (e.g., mica, carbon or animal fiber such as wool) may be mixed in wood fiber. Still further, the same effect can be obtained by using material such as film.
Cloth is used as material of edge 6. However, material of cloth is not limited to this. Material different from material of diaphragm 1 can be used as material of edge 6. For example, the same effect can be obtained by using material such as rubber or urethane.
Speaker 30 may have diaphragm 1 shown in
For example, as shown in
As discussed above, the thickness of the material of part 1D near the top part differs from that of a part other than part 1D near the top part of diaphragm 1. Therefore, the sound-pressure-frequency characteristic, which speaker 30 reproduces, can be flattened further. Whether the thickness of the material of part 1D near the top part increases or decreases is determined by relation of constructional elements such as diaphragm 1, voice coil 3, and frame 5, which compose speaker 30.
As shown in
As shown in
As shown in
In addition, the thickness or the density of the material at part 1D near the top part can be changed drastically, or can be changed gradually with gradation.
SECOND EXEMPLARY EMBODIMENTThe second embodiment is demonstrated hereinafter with reference to the accompanying drawings.
As shown in
Electronic circuit 40 as a main body is structured by fixing and wiring electronic component 42 to circuit board 41. Further, electronic circuit 40 includes amplifier circuit 43 amplifying a voice signal to be supplied to speaker 30. In a word, amplifier circuit 43 is a circuit amplifying the voice signal processed to a sound pressure level which is necessary for outputting it from speaker 30. Amplifier circuit 43 has been integrated into speaker 30 and wired internally. Therefore, a voice output can be easily obtained by coupling speaker module 50 with a voice signal generator (not shown).
Further, electronic circuit 40 may include an additional device such as a voice signal generator or a display circuit besides amplifier circuit 43. For example, in a case of a communication device such as a portable phone, various circuits such as a circuit necessary for communication (e.g., a detecting circuit, a modulating circuit or a demodulating circuit), a driving circuit for a display means (e.g., liquid crystal), a power supply circuit, or a charging circuit can be included.
Using the structure discussed above, speaker 30 and electronic circuit 40, both of which had produced separately and supplied to a production center of an electric device such as a portable phone via an inspection process or a physical distribution process, are integrated each other and modularized. Therefore, a production process, an inspection process and a physical distribution process are integrated, so that tremendous cost reduction is performed.
Accordingly, inexpensive speaker module 50 where speaker 30 and electronic circuit 40 are coupled with each other is provided.
THIRD EXEMPLARY EMBODIMENTThe third embodiment is demonstrated hereinafter with reference to the accompanying drawings.
As shown in
Using the structure discussed above, a device, which is an excellent electric device capable of reproducing sound-pressure-frequency bands ranging broad bands and was not realized conventionally, can be realized not by using plural kinds of speakers having various sound-pressure-frequency characteristics but by using only speaker 30.
Speaker 30 is not limited to be used in component system 54, and can be mounted on various acoustic devices, image devices, communication devices or the like. In a word, it has extremely broad uses in a liquid crystal TV, a plasma display TV, a portable phone or the like.
In addition, height of diaphragm 1 is low, so that the speaker can be thinner. Therefore, an electric device can be thinner and smaller.
FOURTH EXEMPLARY EMBODIMENTThe fourth embodiment is demonstrated hereinafter with reference to the accompanying drawings.
Using the structure discussed above, because speaker 30 which is made thinner and smaller is used, a device such as automobile 60 at which speaker 30 is mounted can be thinner and smaller or free space inside the device can be expanded.
Speaker 30 can be mounted not only at rear tray 61, but also at every place such as front panel 62, a door (not shown), or a side panel (not shown) in automobile 60.
Automobile 60 is described as a device mounting speaker 30, however, the device is not limited to automobile 60, and the same effect can be obtained by using other transporting means such as a bicycle, a motorcycle, a train or an airplane.
INDUSTRIAL APPLICABILITYA speaker, a speaker module, an electric device and a device of the present invention can be adapted to an electric device such as an image acoustic device, an information communication device or a game device, and a device such as an automobile, both of which are desired to be thinner and smaller.
Claims
1. A speaker comprising:
- a frame at which a magnetic circuit is mounted;
- a cylindrical voice coil whose part is placed at a magnetic gap formed by the magnetic circuit;
- an arched diaphragm coupled with the voice coil; and
- an edge linking the diaphragm with the frame and made of material different from that of the diaphragm,
- wherein the diaphragm includes: an inner-diameter-fixing part joined with an end of the voice coil and forming a joining portion whose half apical angle is not larger than 45 degrees; an outer-diameter-fixing part joined with the edge; and a top part formed between the inner-diameter-fixing part and the outer-diameter-fixing part, and protruding forward from the inner-diameter-fixing part and the outer-diameter-fixing part,
- wherein a part near the top part is changed in at least one of thickness and density.
2. The speaker of claim 1,
- wherein material of the diaphragm is wood fiber.
3. The speaker of claim 2,
- wherein the wood fiber includes at least one of kraft pulp, sulfite pulp and material combing kraft pulp and sulfite pulp.
4. The speaker of claim 1,
- wherein material of the edge is cloth.
5. The speaker of claim 1,
- wherein material of the edge is rubber.
6. The speaker of claim 1,
- wherein material of the edge is urethane.
7. The speaker of claim 1,
- wherein material of the diaphragm includes animal fiber.
8. The speaker of claim 1,
- wherein material of the diaphragm includes reinforcing agent.
9. A device comprising:
- a main body; and
- a speaker placed at the main body and including: a frame at which a magnetic circuit is mounted; a cylindrical voice coil whose part is placed at a magnetic gap formed by the magnetic circuit; an arched diaphragm coupled with the voice coil; and an edge linking the diaphragm with the frame and made of material different from that of the diaphragm, wherein the diaphragm includes: an inner-diameter-fixing part joined with an end of the voice coil and forming a joining portion whose half apical angle is not larger than 45 degrees; an outer-diameter-fixing part joined with the edge; and a top part formed between the inner-diameter-fixing part and the outer-diameter-fixing part, and protruding forward from the inner-diameter-fixing part and the outer-diameter-fixing part, wherein a part near the top part is changed in at least one of thickness and density.
10. The device of claim 9,
- wherein the main body includes a circuit for amplifying an input signal to the speaker.
11. The device of claim 9,
- wherein the main body includes a body; a driving member placed at the body; a drive wheel driven by the driving member and supporting the body; a steering placed at the body; a steering wheel operated by the steering,
- wherein the speaker is placed at the body.
Type: Application
Filed: May 16, 2005
Publication Date: Oct 22, 2009
Applicant: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD. (Osaka)
Inventor: Takafumi Yuasa (Mie)
Application Number: 11/569,091
International Classification: H04R 1/00 (20060101);